This proposal describes on going research programs in biochemistry and molecular biology, currently funded by NIH, which would substantially benefit from the capabilities of high mass and high sensitivity mass spectrometry. This proposal requests funds to purchase a laser desorption/time-of-flight mass spectrometer (LD/TOF MS) having a demonstrated mass range of over 100,000 daltons at a sensitivity of 1 pmol or less and at a resolution of _+ 0.01% of the mass range. The primary users are six faculty members in the University of Texas Medical School at Houton who would utilize the spectrometer for both methodology development and specific aplications in biomedical research. The principal investigator, R.M. Capriolo, would utilize the instrument to develop methodology for the structural analysis of proteins using proteases to produce sequence-ordered tryptic maps, cross-linking agents to study ligand-protein and protein-protein binding sites and interchain distances, and utilize exopeptidases to provide sequence data on intact proteins and very large fragment polypeptides. Co-investigators are Finn Wold who will study glycoprotein structure and function; Victoria Knutson, insulin receptor metabolism; Jerry Wolinsky, molecular immune response determinants of Rubella virus; William Dowhan, structure and function of membrane proteins, and Shirish Shenolikar, structure and function of protein phosphatase inhibitor-2. The proposal also lists ten secondary users who would benefit from access to the instrument for occasional use. The instrument would be housed in the Analytical Chemistry Center, a research resource which is supported by the Medical School and serves all of the faculty in the Health Science Center. The LD/TOF mass spectrometer would provide an important complement to existing FAB sector magnetic instrumentation in providing high mass and high sensitivity analyses of biological macromolecules not attainable using current instrumentation.